This invention relates generally to the field of magnetic data storage devices, and more particularly, but not by way of limitation, to improving disc drive assembly and operation through the use of a peripherally extending disc ring affixed to the outermost diameter of each disc in the disc drive.
Disc drives are used as primary data storage devices in modern computer systems and networks. A typical disc drive comprises one or more rigid magnetic storage discs which are journaled about a spindle motor hub to form a rotatable disc stack. An array of read/write transducing heads are provided to transfer data between tracks of the discs and a host computer in which the disc drive is mounted.
High performance disc drives of the present generation rotate the discs at speeds measured in the thousands of revolutions per minute. It is therefore desirable to achieve nominal balance in a disc stack to ensure that data are written and read in a reliable manner and to prevent the generation of undesired vibrations during operation. Disc drive manufacturers typically balance disc stacks by measuring translational and rotational imbalance and then adding one or more discrete weights to the hub of the spindle motor, such as discussed in U.S. Pat. No. 5,130,870 issued to Jabbari and U.S. Pat. No. 5,555,144 issued to Wood et al.
At the same time, disc drives are becoming increasingly smaller and store greater amounts of data, leading to smaller disc thicknesses, closer disc spacings and more delicate read/write heads. Mechanical shocks applied to the drives thus increase the potential for damage as the discs are deflected and contact the rigid actuator arms used to support the heads. Manufacturers have attempted to limit this deflection through the use of deflection limiters (snubbers), such as disclosed in U.S. Pat. No. 5,801,899 issued to Genheimer.
While operable, as rotational speeds and track densities increase, there remains a continued need for improved methodologies for providing disc stack balancing and mechanical shock resistance. It is to such improvements that the present invention is directed.
The present invention provides an apparatus and method for balancing and limiting deflection of a disc stack of a disc drive.
In accordance with preferred embodiments, a disc stack comprises a hub of a spindle motor rotatable about a central axis, one or more discs mounted to the spindle motor hub, and a circumferentially extending peripheral disc ring affixed to an outermost peripheral surface of each disc. After the disc stack is assembled, the imbalance of the disc stack is measured, and portions of the peripheral disc ring are removed in relation to the measured imbalance of the disc stack to nominally balance the disc stack.
Unlike prior art approaches which use a range of discrete weights, substantially nominal balancing can be obtained since the rings can be precisely trimmed in a continuous fashion. Also, the placement of the weights at the outermost circumferences of the discs generally promotes better balancing control as compared to discrete weights placed on the spindle motor hub. The dual function of the rings as both balancers and snubbers reduces part count and assembly time, leading to savings in material and labor costs depending on the extent to which the installation and trimming operation can be automated.
These and various other features and advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.